RelativeLayout.setBackground（）与Drawable导致内存泄漏

Question

我遇到内存泄漏问题。我从http（800KB）下载图像并使用AsyncTask将其存储在Drawable中。下载图像后，内存似乎没问题。但是，在将Drawable设置为RelativeLayout的背景图像后，内存大小增加大约8-10 MEGABYTES。我使用getUsedMem（）来跟踪内存使用情况。如果我使用其中的几个，Android应用程序崩溃与OutOfMemoryException。有谁知道这个问题？如何在此处最小化内存使用量？

public class Example extends Activity {
    private ArrayList<Drawable> drawables;
    private TextView tv;
    private RelativeLayout rl1;

    @SuppressLint("NewApi")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        drawables = new ArrayList<Drawable>();
        tv = (TextView) findViewById(R.id.textView1);
        rl1 = new RelativeLayout(this);

        // Check Memory Before Everything
        printMemory(0);

        // Image url
        String image_url1 = "https://s3-us-west-1.amazonaws.com/example/image.jpg";
        new DownloadFilesTask().execute(image_url1);
    }

    public Drawable drawableFromUrl(String url, String srcName) throws java.net.MalformedURLException, java.io.IOException  {
        InputStream is = (InputStream) new java.net.URL(url).getContent();
        Drawable drawable = Drawable.createFromStream(is, srcName);
        is.close();

        return drawable;
    }

    @SuppressLint("NewApi")
    public void addDrawable(Drawable d) {
        drawables.add(d);
        rl1.setBackground(d);
        printMemory();
    }

    private class DownloadFilesTask extends AsyncTask<String, Drawable, Drawable>   {           
        protected Drawable doInBackground(String... s)       
        {
                    Drawable bgImage = Example.this.drawableFromUrl(s[0], "src name");
                    return bgImage;
         }

        protected void onPostExecute(Drawable drawable)          {
             addDrawable(drawable);
         }
     }

    public long getUsedMem()    {
        long freeSize = 0L;
        long totalSize = 0L;
        long usedSize = -1L;
        try {
            Runtime info = Runtime.getRuntime();
            freeSize = info.freeMemory();
            totalSize = info.totalMemory();
            usedSize = totalSize - freeSize;
        } catch (Exception e) {
            e.printStackTrace();
        }

        return usedSize;
    }

    public long getTotalMem()   {
        long totalSize = 0L;
        try {
            Runtime info = Runtime.getRuntime();
            totalSize = info.totalMemory();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return totalSize;
    }

    public void printMemory()   {
        CharSequence cs = tv.getText();
        tv.setText(cs + "\n" + 
                   "Used Mem: " + getUsedMem() + "\n" +
                   "Total Mem: " + getTotalMem() + "\n" +
                   "Drawables: " + drawables.size());
    }
}